The constraint on OUIGO trains is because tickets have to be checked before onboarding. So you have hundreds of passengers to check in line. This takes time. So

The constraint on OUIGO trains is because tickets have to be checked before onboarding. So you have hundreds of passengers to check in line. This takes time. So people are required to come earlier. However in practice most people respect the 30 minutes, so that you can arrive 10min before the train and get your ticket checked without waiting in line. This is not guaranteed. But often works. I take a lot of OUIGO and never respect the 30 min, because you often wait 10min in line. Once I arrived 5min before departure, had my ticket checked but had to run in front of the correct car. When train arrives nobody is allowed to pass the checkpoint. For the InOui you can always come 5min before departure, because tickets are checked on-board so there is no wait line.